Project Summary/Abstract Proteins lie at the nodes of signaling pathways, and it is their task to integrate these signals to direct a specific output - one that is tailored to the needs of the cell at the time. Dr. Miles Pufall has studied signal integration using the glucocorticoid receptor (GR), in particular the mechanistic basis of allosteric regulation by DNA sequence. This K99/R00 award will provide him with the resources, time, and training to develop systems that translate the structural and biophysical basis of GR allosteric integration into an understanding of the signaling aberrations that result in childhood pre-B acute lymphoblastic leukemia (B-ALL) treatment resistance. This work will enable development of selective interventions that direct allosteric networks in the protein. This award will allow Dr. Pufall to achieve the following career development goals: 1) Develop a grounding in hematopoietic development and disease; 2) Learn to work with primary tissue; 3) Gain experience with genomic data sets to develop future studies; and 4) Develop an in vitro system to test signal integration principles. The glucocorticoid receptor orchestrates a program of gene expression in response to cellular signals by nucleating the assembly of regulatory complexes at specific DNA response elements throughout the genome. In B-ALL, synthetic glucocorticoids directed against GR are an effective treatment, which in combination with other drugs, work to induce an apoptotic program. However those who do not respond to glucocorticoids face a grim prognosis. Dr. Pufall hypothesizes that signaling pathways that allosterically regulate GR have been disrupted, changing the normal function of the receptor, and blocking apoptosis. He will test this hypothesis in three aims: 1) Identify changes in glucocorticoid induced gene expression programs, GR binding, and marks for active chromatin in glucocorticoid sensitive and resistant acute lymphoblastic leukemia; 2) Purify GR regulatory complexes from select response elements and identify components; and 3) Identify allosteric wires emanating from the DNA binding domain of GR, and determine how signals impinge on these wires.